1. Field of the Invention
The present invention relates to a novel system and method for terminating cover crops by rolling and crimping.
2. Description of the Related Art
Cover crops are a vital part of conservation tillage systems, but they have to be managed appropriately to get their full benefit. This includes improved soil physical properties and mulch effects, increased soil organic matter, and reduced weed pressure caused by alleopathy. In the Southern United States, rye is commonly used as a winter cover crop. Timely termination of cover crops before a cash crop planting provides maximum benefits to the main crop. Mechanical rollers have been used in some conservation systems but high vibrations and low operating speeds associated with the current roller designs have resulted in a low rate of adoption by farmers.
A report by Conservation Tillage Information Center (CTIC) (Conservation Tillage Trends, 1990-2002, National Crop Residue Management Survey, 2003) shows that between 1990 and 2002, the number of United States cropland acres planted in conservation systems without surface tillage increased from 73.2 million acres to 103.1 million acres. This significant increase can be attributed by positive benefits of winter cover crops as an integral component of conservation tillage systems. Several studies have identified these benefits, such as increased water infiltration, reduced runoff, reduced soil erosion, and reduced detrimental effects of soil compaction (Reeves, In. J. L. Hatfield and B. A. Stewart (ed.), Advances In Soil Science: Crops Residue Management, Lewis Publishers, Boca Raton, Fla., 1994; Raper et al., Applied Eng. Agric, Volume 16 (4), 379-385, 2000a; Raper et al., J. Cotton Sci., Volume 4(2), 84-90, 2000b).
Most agricultural extension services recommend terminating the cover crop at least two weeks prior to planting a cash crop. This should prevent the cover crop from using valuable spring moisture that could be used by the main cash crop after planting. Killing cover crops has been accomplished by several methods with the use of herbicides as the main method, since spraying is relatively fast and inexpensive. However, planting after a chemical kill can sometimes be difficult if the cover crop has been allowed to become too large and lodged in multiple directions. This may hamper the ability of a planter with conservation tillage attachments from being successful in moving or cutting the residue and placing the seed properly in a soil furrow.
Another method that has been used to terminate the cover crop is mowing. This option may also pose problems because cover crops can sometimes re-sprout and compete with the cash crop for available moisture and nutrients. Also, the unattached crop residue can make the planting operation difficult as row cleaners can become clogged with loose residue and require frequent cleaning.
Flattening and crimping cover crops by mechanical rollers is widely used in South America, especially Brazil, to successfully terminate cover crop without the need of using herbicides. Because of potential environmental and monetary benefits (no use of herbicides), this technology is now receiving increased interest in North America. Implements for this purpose are usually round drums with equally spaced blunt bars around the drums perimeter. As the device is rolled across the field, the bars crimp or crush the stalks of the cover crop, causing death of the plants. In this method, the purpose of the bars is to crimp or crush the stems and not to cut them. If stems are cut, the cover crop can re-sprout. Ashford and Reeves (American Journal of Alternative Agriculture, Volume 18(1), 37-45, 2003) investigated benefits of rolling a cover crop. They indicated that when rolling was conducted at the correct stage of plant growth, the roller was equally effective as chemical herbicides at terminated the cover crop. They also indicated that the power required for rolling was significantly reduced, as much as tenfold, compared to the amount of power required to mow. Another important aspect of rolling is that a flat mat of cover crop lies in the direction of travel allowing farmers to use planter-seeders operating in parallel or slightly off parallel to the rolled cover crop direction which has been successful in obtaining proper plant establishment.
Despite these advances, some North American producers have reported problems with these implements. The main complaint has been the excessive vibration that the rollers generate. Research has shown that vibrations generated by agricultural equipment have detrimental effects on an operator's health including increased heart rate, headache, stomach pain, and lower back pain, and from long exposure: spinal degeneration (Bovenzi, Semin Perinatol. 20: 38-53.1996; Toren et al., Applied Ergonomics 33:139-146.2002; Muzammil et al., Journal of Occupational Health. 46: 403-409, 2004). The most effective method of alleviating the vibration, but not desirable and not economical, has been to reduce travel speed. Most producers find this to be an unacceptable solution due to the much higher operating speeds (about 6.4 km/hour) that they were able to use to spray herbicides on their crops
Raper et al., U.S. patent application Ser. No. 10/747,459, filed Dec. 12, 2003, disclose an apparatus that is rolled across a field at relatively high speed without excessive vibration. The apparatus includes a substantially cylindrical drum having a plurality of rows of outwardly extending crimping bars projecting from the drum. The bars can be wave-shaped, curved, substantially straight and discontinuous bars paired with a plurality of spaced apart outwardly extending rings.
While various methods and apparatus are used for terminating cover crops prior to planting a cash crop using a conservation system, there remains a need for systems and methods for terminating cash crops which prevent re-sprouting of the cover crop, do not interfere with the planting of a cash crop, and at least reduces the vibrations so that termination operations are not slowed down. The present invention provides a system for terminating a cover crop which is different from related art systems and solves some of the problems of the prior art.